A Case of Esophageal Retention Cyst with High Fluorodeoxyglucose Uptake on PET/CT Scan.

Introduction: Esophageal retention cysts are rare, benign lesions that can mimic submucosal tumors. Their clinical presentation and imaging characteristics may lead to diagnostic challenges, particularly when fluorodeoxyglucose-positron emission tomography/CT (FDG-PET/CT) shows increased uptake, raising suspicion of malignancy.

Case Presentation: A 77-year-old man presented with epigastric pain. Upper gastrointestinal endoscopy revealed an esophageal mass, prompting referral to our hospital. Endoscopic ultrasonography (EUS) identified a hypoechoic submucosal tumor with multiple cystic components in the lower esophagus. However, EUS-guided fine-needle aspiration (EUS-FNA) did not yield a definitive diagnosis. CT scan demonstrated a 60-mm space-occupying lesion (SOL) in the lower thoracic esophagus with peripheral contrast enhancement and a central low-density area. MRI revealed a SOL in the lower esophagus with high signal intensity on T2-weighted images and moderate signal intensity on T1-weighted images. The lesion contained cystic components exhibiting high T2 and low T1 signal intensities. FDG-PET/CT revealed intense FDG uptake, increasing from maximum standardized uptake value (SUVmax) 11 to 18 over time. Given the large size of the tumor, symptomatology, and inability to exclude malignancy-particularly high-risk gastrointestinal stromal tumor-surgical resection was performed. Laparoscopic esophagectomy was conducted using intraoperative endoscopy for tumor identification. The esophagus was transected proximally using a linear stapler, followed by extracorporeal gastric conduit reconstruction and the overlap technique was used to perform an esophagogastric anastomosis. Postoperatively, anastomotic leakage was detected on day 3, requiring emergency reoperation. The leak had resolved by POD 26, and the patient was discharged on day 48 after the second surgery (day 51 after the initial surgery). Histopathological examination revealed multiple cysts of varying sizes within the lamina propria, lined by columnar epithelium, with no evidence of malignancy. The final diagnosis was esophageal retention cyst.

Conclusions: This case highlights the diagnostic challenge of esophageal retention cysts with high FDG uptake. While PET/CT is essential in oncologic imaging, FDG accumulation does not always indicate malignancy.